1. Field of the Invention
Embodiments disclosed herein relate generally to methods for forming breathable articles, and breathable articles formed using those methods.
2. Background
Coverings, such as gloves, mitts, socks, shoes, or boots, long have been used to protect hands and feet from environmental or work conditions. Depending on the type of environment, nature of work, or desired properties, these type of coverings have been made from a variety of materials, which have included woven cloth fabrics, leather, natural latex or synthetic polymer elastomeric materials, or combinations of such materials. These articles typically have been designed for durable use.
The vast majority of gloves or foot covers, typically, have been made from either woven cloth fabrics, suede, or leather. Gloves made of woven fabrics generally allow the skin of the wearer to breathe through the spaces between the individual strands of woven fabric material, and any perspiration from the hand or foot is wicked away by the fabric. Leather tends not to fit as comfortably as cloth or fabric-lined articles, nor is it as flexible, or permits the skin to breathe as easily. Moreover, leather, while resilient, typically is not as good of a barrier against prolonged exposure to wetness or hazards as polymeric elastomer materials.
For applications that require greater protection against fluids, chemicals, or microscopic pathogens, such as found in laboratory, healthcare and clinical, or other work settings, the protective articles—gloves in particular—traditionally have incorporated a barrier layer that is impervious to the undesirable substances. Surgical, examination, or work gloves, for example, typically are made using natural or synthetic rubber latex or other elastic polymer membranes, which generally exhibit good barrier properties. Unfortunately, the good barrier properties of such materials may create a harsh environment for the wearer's skin, which is bad for skin/hand health.
For example, wearing a glove made from an elastic polymer latex for prolonged periods can trap perspiration in the article because the wearer's skin is not able to adequately breathe, making the glove uncomfortable to wear. As perspiration accumulates, the moist environment within the article may become a potential source or incubator for the growth of fungi or yeast, as well as bacterial or viral contamination, which can exacerbate skin problems.
People have tried to solve these problems in a variety of ways, for instance, by combining woven and elastomeric materials. A common practice has been to unite a woven or cloth-like material as an underlayer with an elastomeric membrane or film as a barrier overcoat, for a strong and resistant article (e.g., as described in U.S. Pat. No. 2,060,961, or 5,246,658, or U.S. Patent Publication No. 2004/0139529). Manufacturers have used knit, woven, or non-woven fabrics as liners in a variety of durable industrial gloves that can have a relatively long work life. Such gloves can be made in a variety of ways. For instance, as described in the patent examples, gloves are fabricated by providing a hand-shaped block mould or former, applying or fitting a woven or knit glove-shaped liner, then dipping into a polymer solution, such as latex or nitrile, to cover the glove liner.
Typically, the liners for such gloves are generally thick, hence gloves made from this type of processes usually have poor flexibility and fit loosely to the hand. In some other cases, fabrics are first laminated to a polymer layer and then sealed under harsh conditions to form an air and water-proof seam, such as described in U.S. Pat. No. 5,981,019, which discloses an air and liquid-proof protective cover for use in harsh environments. Furthermore, the configuration of the human hand is such that the thumb projects considerably beyond the palm, and the thumb and other four fingers can move relatively freely in relation to each other to perform any desired task.
Gloves that are made according to conventional methods are often made on a flat hand-shaped dipping mould or a last. Since a hand or foot has three-dimensionality, gloves or foot covers that are made in largely flat moulds do not fit the hand or foot well when worn and feel uncomfortable, which can be cumbersome when working.
According to other approaches, manufacturers fabricate elastomeric articles reinforced with fibers. Common work gloves, such as for housework or industrial uses, are examples of this latter design. Manufacturers of fiber-reinforced gloves incorporate an internal lining composed of fibrous material, such as cotton flock (e.g., U.S. Pat. Nos. 4,918,754, 4,536,890, or 5,581,812). Typically, flock is composed of finely divided, short, ground, fibrous particles, which can be applied as a lining by spraying the flock particles onto an adhesive-covered backing (e.g., the external shell of a glove). An inner glove lining of flock provides a smooth, comfortable feeling, cushions the hands, absorbs perspiration and keeps the hands dry, insulates against moderate heat and cold without being bulky, makes the glove easier to put on and take off, and has other advantageous characteristics. Gloves with such characteristics are favored by workers and have become common articles for various heavy-duty industrial applications.
The disadvantages, however, of a glove having an internal lining composed of cotton flock or other similar fibrous material are many. First, for instance, fibers and particles can become detached from the internal lining over time through abrasion with either the glove wearer's hand or the surface of the sleeve of a garment worn by the wearer. The detached particles can migrate out of the glove, particularly when the glove is being donned or removed from the wearer's hand.
Second, fibers, like short cotton fibers, typically are not elastomeric, which makes them difficult to coat onto glove skins made of latex or nitrile materials, etc. The current commercial flocking process uses glue to make the short cotton fibers stick. Flocking is essentially a batch process, and fibers can not be embedded into the polymer layers effectively.
Like in elastomeric articles, current-commercial flocked gloves, in some cases, use powder, such as cornstarch or calcium carbonate powders, to enhance the donning and comfort. The presence of powders may help absorb some of the perspiration moisture and alleviate some of the problems the wearer faces. The use of powder, however, was only partially successful, as the powder particles could absorb only a limited amount of the moisture. Additionally, powders are not well accepted among consumers because of allergy and health concerns of small particles, or for certain uses, such as in clean-room type applications and during surgical procedures, powders may not be used at all.
Aside from industrial-type gloves with cotton liners or fabric liners, currently very few examples of disposable gloves exist that incorporate coated fibers, which can provide qualities such as comfort, good fit with flexibility, easy donning or insertion of the hand, being powder-free, allergy prevention, skin protection, and moisture absorption. For disposable latex gloves, the challenge is to create an elastomeric fiber-layer without limiting the fiber length and size to make economically viable flexible, fiber-lined, disposable gloves. Unfortunately, current technologies for durable industrial gloves cannot satisfy this challenge.